1. Field of the Invention
The present invention relates to a process for the preparation of a silicon-modified thermoplastic resin having a good transparency, heat resistance, impact resistance, moldability and mechanical strength
2. Description of the Related Art
An imide group-containing resin has an excellent heat resistance such that the practical use temperature is 120.degree. to 220.degree. C., this heat resistance can be varied by changing the content of the imide monomer unit, and the imide group-containing resin has a relatively good balance of properties such as transparency, mechanical properties and moldability. Therefore, the imide group-containing resin is widely used in various fields for automobile parts, electric parts, additive polymers to polymer alloys, and the like, and other uses of this resin as a resin having especially good heat resistance and moldability in combination have been investigated and developed.
Nevertheless, this resin does not have a satisfactory impact strength; and for example, the notched impact strength is 3 to 7 kg.cm/cm (23.degree. C., 3.2 mm in thickness), and further, the saturation water absorption is as high as 0.2 to 1%. Accordingly, there is an urgent used to improve the impact resistance and reduce the water absorption, while maintaining the original high heat resistance and transparency.
As the means for improving the impact resistance of an imide group-containing thermoplastic resin, there have been proposed a method in which a graft polymer formed by grafting styrene, acrylonitrile or methyl methacrylate to a butadiene polymer or a styrene/butadiene copolymer, such as an ABS resin or an MBS resin, is blended in the above-mentioned imide group-containing resin, a method in which a graft polymer formed by grafting styrene or methyl methacrylate to polybutyl acrylate or a butadiene/butyl acrylate copolymer is blended in the above-mentioned imide group-containing resin, and a method in which a polycarbonate is blended in the above-mentioned imide group-containing resin.
According to these proposals, the impact resistance is improved, but the characteristics of the imide group-containing thermoplastic resin, especially the transparency and heat resistance, are drastically degraded and therefore, many practical problems remain unsolved.